Method of making metallic containers for confining fluid medium under pressure



June 25, 1956 MAPES 2,751,677

METHOD OF MAKING METALLIC CONTAINERS FOR CONFINING FLUID MEDIUM UNDER PRESSURE Filed July 9, 1952 INVEN TOR. fiazzz'efzllapes J /2 ATTORNEY United States Patent METHOD OF MAKING METALLIC CONTAINERS FOR CONFINING FLUID MEDIUM UNDER PRESSURE Daniel Mapes, West Caldwell, N. J assignor to Specialties Development Corporation, Belleville, N. L, a corporation of New Jersey Application July 9, 1952, Serial No. 297,880

1 Claim. (Cl. 29-543) The present invention relates to a method of making metallic containers for storing fluid media under pressure, such as compressed and/or liquefied normally gaseous materials; and, more particularly, relates to an improved method of making such containers which will either resist gunfire or will not shatter when pierced by a projectile.

Containers of the foregoing character are widely used on military craft or vehicles, and may be subjected to machine gunfire when in a combat area. The universal use of high-powered, high-caliber machine gun ammunition requires that such containers be reinforced, particularly at the side wall thereof, to prevent shattering or violent ripping apart when struck by the projectiles of such ammunition.

For example, as shown in my prior Patent No. 2,370,677, such reinforced containers generally comprise a one-piece, substantially rigid, seamlessly formed metallic cylinder which is inherently subject to ripping apart when pierced by a projectile and which is constructed to withstand the highest working pressures at which fluid media may be confined therein under normal conditions of use without further reinforcement; and a continuous winding of contiguous convolutions of steel piano wire of high tensile strength on the side wall of the container. While reinforced containers of the foregoing type will not shatter or rip apart when subjected to gunfire, the applied winding involves additional manufacturing operations which increase the cost of the containers.

Accordingly, an object of the present invention is to provide a simple, practical and economical method of making gunfire resistive containers.

Another object is to provide a method of making such containers which are so constructed that the application of additional reinforcing structure is not required.

A further object is to provide a method of making such containers wherein the thickness of the container walls is readily controlled to attain the desired reinforcement.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claim, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

In accordance with the present invention, the foregoing objects are accomplished by providing an improved method of making cylindrical metal containers for confining fluid media under pressure which method includes the steps of forming a cylindrical sheet metal cup having an end wall and a side wall of substantially uniform thickness, drawing the cup to form a cylindrical shell of greater length and smaller diameter than the cup while maintaining the thickness of the end wall and the side wall substantially uniform, and extending the end wall axially outwardly while shaping the same into a substantially hemispherical end wall or bottom having a thickness about half that of the side wall. The method further includes the steps of reducing the thickness of 2,751,677 Patented June 26, 1956 the side wall at a cylindrical zone adjacent the open end of the shell to about that of the end wall, and then necking the zone to form a substantially hemispherical end wall or dome adapted to be provided with an outlet.

A preferred embodiment of the invention has been chosen for purposes of illustration and description, and is shown in the accompanying drawing, forming a part of the specification, wherein:

Figure l is a perspective view of a circular blank or sheet metal from which a container in accordance with the invention is formed.

Figure 2 is a sectional view of a cylindrical cup formed from the blank.

Figure 3 is a sectional view of a cylindrical shell formed from the cup.

Figure 4 is a sectional view of the shell after being further lengthened and reduced in diameter.

Figure 5 is a sectional view of the shell shown in Figure 4 with the closed end wall extend axially outwardly to reduce the thickness thereof.

Figure 6 is a sectional view of the shell shown in Figure 5 but provided with a cylindrical zone of reducedopposite the wall 12. The cup is formed in any conventional manner, but preferably the side and end walls are of substantially uniform thickness throughout.

The cup 11 is shaped into a shell 150f greater length and smaller diameter than the cup, preferably by progressively either hot or cold drawing the cup in several steps as illustrated in Figures 3 and 4 to produce the completed shell shown in Figure 4. In forming the shell 15, the flat shape of the bottom or end wall 12 is maintained and the thickness of the side and end walls is maintained substantially uniform.

The end wall is then bulged or extended axially outwardly while shaping the same into a substantially hemispherical end wall 16 of reduced thickness (Figure 5). This may be accomplished in a number of different ways. For example, the end Wall could be cold worked or coined in a press by means of a punch and die. However, the end wall preferably is heated to facilitate flow of the metal and a punch or gas pressure may be applied to extend it outwardly while shaping the same and reducing the thickness. Reduction in thickness may also be accomplished by machining rather than by working the metal either hot or cold if desired.

As shown in Figure 6, a cylindrical zone 17 of reduced thickness is then provided adjacent the open end of the shell. This again may be accomplished in a number of different ways. For example, such reduction of thickness may be attained by either hot or cold drawing or spinning or swaging this zone. Likewise, the zone of reduced thickness can be provided by machining. Also, the reduction in thickness may be effected at either the inside or outside of the shell or partially at both the inside and outside of the shell.

The length of the zone 17 is such that the zone can be shaped into a substantially hemispherical dome 19 (Figure 7) adapted to be provided with an outlet spud 2t). The dome may be formed by spinning or press necking the zone 17 inwardly, preferably while hot, to close the open end of the container.

The container, shown in Figure 7 and made in accordance with the method of the present invention just described, comprises a cylindrical side wall 21 of substantially uniform thickness throughout, a hemispherical bottom or end wall 16 having a thickness about half that of the side wall, and a hemispherical dome 19 having a thickness about equal to that of the end wall 16. The thickness of the end wall and dome is about 'equal to the side wall thickness of a container constructed to safely withstand the highest working pressures at which fluid media may be confined therein under normal conditions of use without further reinforcement, while the thickness of the side wall 21 is about double the side wall thickness of such a container. Thus by providing a blank 10 of a predetermined thickness and diameter, a flat bottom shell of double side and end wall thickness can be readily shaped therefrom. This flat end wall is then shaped into a hemispherical wall of. reduced thickness simply by extending the flat bottom outwardly. Reduction of the thickness of the dome wall likewise is effected in a convenient manner.

It has been found that the double side Wall thickness provides a container which will either resist gunfire or will not shatter when the side wall is pierced while fluid media under pressure isstored therein. The end wall and dome of reduced thickness by reason of their generally hemispherical shape, are equally as strong as the thick cylindrical side wall and are thus also capable of resisting gunfire and/or preventing shattering or ripping apart of the container.

From the foregoing description, it will be seen that the present invention provides a simple, practical and economical method of forming such containers which do not require any additional reinforcing structure.

As various changes may be made in the form, construction and arrangement of the parts herein, without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in any limiting sense.

I claim:

The method of making a metal one-piece, seamlessly formed cylindrical container for storing compressed fluid medium under pressure and having a cylindrical side wall of a predetermined substantially uniform thickness and having substantially hemispherical end walls of a thickness about equal to about half that of the side wall and about equal to the side wall thickness of a cylindrical container of equal capacity constructed to withstand the highest working pressures at which fluid medium may be safely confined therein under normal conditions of use without further reinforcement, which method consists of forming a circular steel plate into a cylindrical cup provided with a substantially flat end wall and a side wall each having a. substantially uniform and equal thickness, drawing the cup in stages to form a cylindrical shell of greater length and smaller diameter than the cup while maintaining the thicknesses of the end wall and of the side wall substantially uniform and equal to each other, extending the end wall outwardly while shaping the same into a hemispherical end wall having a thickness about half that of the side wall, reducing the thickness of the side wall at a cylindrical zone adjacent the open end of the shell to about half that of the side wall, and necking the zone to form a substantially hemispherical end wall of a thickness about equal to that of the first formed end wall.

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